[GHC] #8371: ghci byte compiler + FFI crashes when used with embedded R

[Dominick Samperi]

After further testing it appears this work-around is not enough.
It needs to be combined with another suggestion in this
thread: must use ghc-7.7. There is a segfault (but no
"C stack usage" message) when ghc-7.6.3 is used.

Thank you!



On Sat, Sep 28, 2013 at 10:08 AM, Dominick Samperi <djsamperi at gmail.com>wrote:

> Thanks! Turning off R's stack limit checks will not work. I tried this
> and this leads to a segfault. Fortunately, your experiments led me
> to a work-around: simply use the -fno-ghci-sandbox flag.
>
> R is not thread-safe, and this flag tells ghci to run computations
> in the main thread instead of forking.
>
>
> On Sat, Sep 28, 2013 at 1:29 AM, GHC <ghc-devs at haskell.org> wrote:
>
>> #8371: ghci byte compiler + FFI crashes when used with embedded R
>> -------------------------------+----------------------------------
>>         Reporter:  dsamperi    |            Owner:
>>             Type:  bug         |           Status:  new
>>         Priority:  normal      |        Milestone:
>>        Component:  GHCi        |          Version:  7.6.3
>>       Resolution:              |         Keywords:
>> Operating System:  Linux       |     Architecture:  x86_64 (amd64)
>>  Type of failure:  GHCi crash  |       Difficulty:  Unknown
>>        Test Case:              |       Blocked By:
>>         Blocking:              |  Related Tickets:
>> -------------------------------+----------------------------------
>>
>> Comment (by rwbarton):
>>
>>  I can reproduce this without ghci, by putting a forkIO around the body of
>>  main (and adding a threadDelay in the main thread).
>>
>>  It seems to just be an interaction between R's method for determining the
>>  base address of the stack and the way pthread allocates stacks for new
>>  threads. Try this C example program `pt.c`.
>>
>>  {{{
>>  #include <stdio.h>
>>  #include <unistd.h>
>>  #include <pthread.h>
>>
>>  int Rf_initEmbeddedR(int argc, char **argv);
>>
>>  void *foo(void *blah)
>>  {
>>      char *args[] = {"pt", "--gui=none", "--silent", "--vanilla"};
>>      int r;
>>      setenv("R_HOME", "/usr/lib/R", 1);
>>      r = Rf_initEmbeddedR(sizeof(args)/sizeof(args[0]), args);
>>      printf("r = %d\n", r);
>>  }
>>
>>  int main(void)
>>  {
>>      pthread_t tid;
>>      pthread_create(&tid, NULL, foo, NULL);
>>      while (1)
>>          sleep(1);
>>      return 0;
>>  }
>>  }}}
>>
>>  {{{
>>  rwbarton at adjunction:/tmp$ gcc -o pt pt.c  -lpthread -lR
>>  rwbarton at adjunction:/tmp$ ./pt
>>  Error: C stack usage is too close to the limit
>>  Error: C stack usage is too close to the limit
>>  r = 1
>>  }}}
>>
>>  It would probably be best to just disable R's stack limit checks, if
>>  possible.
>>
>> --
>> Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8371#comment:6>
>> GHC <http://www.haskell.org/ghc/>
>> The Glasgow Haskell Compiler
>>
>
>
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